'Chip' one of the two tunnel boring machines creating drift tunnels for the Billy Bishop Toronto City Airport Pedestrian Tunnel breaks through the wall of the island shaft. (CNW Group/Toronto Port Authority)

TORONTO, Jan. 29, 2013 /CNW/ - 'Chip', one of the two tunnel boring
machines being used to construct the pedestrian walkway to Billy BishopToronto City Airport, has completed one of the drift tunnels and broken
through the tunnel's shaft wall on Toronto Island.

The Canadian-made tunnel boring machine was lowered into the tunnel
shaft at the foot of Eireann Quay on January 10 and began drilling on
January 12. Its twin, 'Dale', is currently beneath the Western Gap
creating one of seven drift tunnels that will form the walkway's crown.
'Chip' will be returned to the mainland to begin work on the next drift
tunnel.

The walkway crown will be arched and comprise seven smaller,
interlocking tunnels (six feet/1.8 metres) designed to reduce the
potential for water ingress during construction. These tunnels will be
constructed to form an arched roof for the walkway. Three of the drift
tunnels will carry city mains to the Toronto Islands.

The Toronto Port Authority is building a pedestrian walkway across the
Western Gap to Billy BishopToronto City Airport. The 800-foot walkway
will be completed in Spring 2014 and will be the only known pedestrian
tunnel in the world that connects to an airport and sits beneath a body
of water.

The Toronto Port Authority (TPA) owns and operates Billy BishopToronto
City Airport, the Port of Toronto (Terminals 51 and 52), and Toronto's
Outer Harbour Marina. In addition to moving more than two million
passengers through the airport in 2012, the Port Authority provides
transportation, distribution, storage and container services to
businesses at the Port, and owns and operates Toronto's largest
freshwater marina. The Toronto Port Authority was incorporated on June
8, 1999 as a government business under the Canada Marine Act as the
successor to the Toronto Harbour Commissioners.